Phase behaviour and development scheme of near-critical gas condensate reservoir

Abstract

Combined with fluid data of J gas reservoir in Africa, the phase characteristics of near-critical gas condensate reservoir were studied, and the applicable development technique were analyzed using reservoir numerical simulation. The results show that the near-critical gas has the following characteristics. It has a high content of condensate oil, the sensitivity of phase is strong, and the degree of retrograde condensation is high. Depletion type of recovery results in great loss of condensate oil and poor production, the method of water-oil alternating recovery could control the level of condensate effectively and get a high oil production rate. In addition, it avoids the rising up of water cut too early and quickly in the method of water flooding. Water-oil alternating recovery is the best producing method which combined the advantages of water injection and gas injection. Further study on sensible factors in water-oil alternating recovery indicates that the water/ gas ratio (WGR) has the greatest impact on production effect. When the WGR is too high, injected water will rush into the well bottom too early; when the WGR is too low, the advantage of water injection to displace and provide pressure is lost, and condensate oil production rate cannot be enhanced.